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Replaces KDF

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Uses H(txid) for locator and H(txid|txid) for master_key now
This commit is contained in:
Sergi Delgado Segura
2019-06-20 18:26:34 +01:00
parent c7ba4fb423
commit dd3dee5b7a
2 changed files with 15 additions and 35 deletions
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25
pisa-btc/apps/blob.py
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@@ -1,9 +1,7 @@
from binascii import hexlify, unhexlify
from hashlib import sha256
from cryptography.hazmat.primitives.ciphers.aead import AESGCM
from cryptography.hazmat.primitives.kdf.hkdf import HKDF
from cryptography.hazmat.primitives import hashes
from cryptography.hazmat.backends import default_backend
from conf import SALT, SUPPORTED_HASH_FUNCTIONS, SUPPORTED_CIPHERS
from conf import SUPPORTED_HASH_FUNCTIONS, SUPPORTED_CIPHERS
class Blob:
@@ -31,19 +29,12 @@ class Blob:
# Extend the key using HKDF
tx_id = unhexlify(tx_id)
hkdf = HKDF(
algorithm=hashes.SHA256(),
length=32,
salt=SALT.encode(),
info=None,
backend=default_backend()
)
# master_key = H(tx_id | tx_id)
master_key = sha256(tx_id + tx_id).digest()
extended_key = hkdf.derive(tx_id[16:])
# The 16 MSB of the extended key will serve as the AES GCM 128 secret key. The 16 LSB will serve as the IV.
sk = extended_key[:16]
nonce = extended_key[16:]
# The 16 MSB of the master key will serve as the AES GCM 128 secret key. The 16 LSB will serve as the IV.
sk = master_key[:16]
nonce = master_key[16:]
# Encrypt the data
aesgcm = AESGCM(sk)
@@ -52,7 +43,7 @@ class Blob:
if debug:
logging.info("[Client] creating new blob")
logging.info("[Client] master key: {}".format(hexlify(tx_id[16:]).decode()))
logging.info("[Client] master key: {}".format(hexlify(master_key).decode()))
logging.info("[Client] sk: {}".format(hexlify(sk).decode()))
logging.info("[Client] nonce: {}".format(hexlify(nonce).decode()))
logging.info("[Client] encrypted_blob: {}".format(encrypted_blob))

25
pisa-btc/pisa/encrypted_blob.py
View File

@@ -1,9 +1,6 @@
from binascii import unhexlify, hexlify
from hashlib import sha256
from cryptography.hazmat.primitives.ciphers.aead import AESGCM
from cryptography.hazmat.primitives.kdf.hkdf import HKDF
from cryptography.hazmat.primitives import hashes
from cryptography.hazmat.backends import default_backend
from conf import SALT
class EncryptedBlob:
@@ -11,24 +8,16 @@ class EncryptedBlob:
self.data = data
def decrypt(self, key, debug, logging):
# Extend the key using HKDF
hkdf = HKDF(
algorithm=hashes.SHA256(),
length=32,
salt=SALT.encode(),
info=None,
backend=default_backend()
)
# master_key = H(tx_id | tx_id)
master_key = sha256(key + key).digest()
extended_key = hkdf.derive(key)
# The 16 MSB of the extended key will serve as the AES GCM 128 secret key. The 16 LSB will serve as the IV.
sk = extended_key[:16]
nonce = extended_key[16:]
# The 16 MSB of the master key will serve as the AES GCM 128 secret key. The 16 LSB will serve as the IV.
sk = master_key[:16]
nonce = master_key[16:]
if debug:
logging.info("[Watcher] creating new blob")
logging.info("[Watcher] master key: {}".format(hexlify(key).decode()))
logging.info("[Watcher] master key: {}".format(hexlify(master_key).decode()))
logging.info("[Watcher] sk: {}".format(hexlify(sk).decode()))
logging.info("[Watcher] nonce: {}".format(hexlify(nonce).decode()))
logging.info("[Watcher] encrypted_blob: {}".format(self.data))